1. Field of the Invention
This invention relates to an optical transmitting device to be used for an optical fiber communication system in order to transmit optical signals with a high-output power level and, more particularly, it relates to an optical transmitting device designed to prevent optical signals being transmitted out of it along an optical path from being inadvertently emitted out of the optical path as any of the optical connectors of the system is displaced or removed.
2. Prior Art
An optical transmitting device for transmitting optical signals in an optical fiber communication system is typically designed to produce optical signals with a high-output power level so that the signals may travel over a long distance without being strained or lost.
Such a communication system operates well as long as the optical connectors are connected properly in the optical path. However, signal light can leak out with a high-power level and signals can be strained or lost once any of the connectors is displaced or dislocated.
Signal light with a high-power level can be dangerous to the human body particularly when it hits the eyes and, therefore, the operation of installing, replacing and removing connectors while high-power signal light is being transmitted cannot be carried out without providing some security and protection measures.
The most simple security measure that can be provided may be suspension of the operation of the optical transmitting device. However, suspension of the operation of the optical transmitting device entails blackout of all the transmission paths connected to the optical transmitting device, which can bring forth serious consequences.
In an attempt to avoid this problem, Japanese Patent Applications Laid-Open Nos. 3-13909 and 6-177837 disclose a technique of detecting the dislocation of an optical connector and automatically reducing the power level of the light source of the optical transmitting device so that leaked signal light, if any, may not damage the operator working at the optical connector where signal light is leaking.
However, with any of the techniques disclosed in the above patent documents, if the signal light output power level of an optical transmitting device having a plurality of optical output ports that are covered by a single light source is reduced, the output power level of the optical output ports having no optical paths with a displaced or removed optical connector are also reduced to consequently produce degraded signal light in every optical path.
In view of the above problem, it is therefore the object of the present invention to provide an optical transmitting device with which signal light can be blocked only in the optical path having a displaced or removed optical connector without affecting the remaining optical paths.